Method and system to ensure full oil tubes after gas turbine engine shutdown

Abstract

A method of operating a lubrication system for a gas turbine engine includes pumping a lubricant from a supply conduit to a bearing compartment. A pressure differential in the bearing compartment. The supply conduit is evacuated in response to the pressure differential creating step. The supply conduit is refilled with the lubricant from a reservoir conduit fluidly joined to the supply conduit at a junction by gravitationally draining the reservoir conduit.

What is claimed is: 
     
       1. A method of operating a lubrication system for a gas turbine engine, the method comprising:
 pumping a lubricant from a supply conduit to a bearing compartment; 
 creating a pressure differential in the bearing compartment; 
 evacuating the supply conduit in response to the pressure differential creating step; 
 refilling the supply conduit with the lubricant from a reservoir conduit fluidly joined to the supply conduit at a junction by gravitationally draining the reservoir conduit; and 
 wherein the lubrication system includes a main pump fluidly connected to the bearing compartment by a supply line, and the pumping step includes providing lubricant to the bearing compartment through a supply line that splits into the supply conduit and the reservoir conduit that are fluidly parallel to one another for a length before rejoining with one another at the junction. 
 
     
     
       2. The method according to  claim 1 , wherein the reservoir conduit includes a flow restrictor upstream from the junction, and the refilling step includes filling the supply conduit through the flow restrictor more slowly than the lubricant is evacuated from the supply conduit. 
     
     
       3. The method according to  claim 2 , wherein the supply conduit includes a U-shaped portion gravitationally below the junction and the bearing compartment in a normal engine operating condition, and the U-shaped portion includes the flow meter downstream from the junction. 
     
     
       4. The method according to  claim 3 , wherein the U-shaped portion includes legs, and the refilling step includes filling the legs. 
     
     
       5. The method according to  claim 1 , comprising a step of scavenging the lubricant from the bearing compartment while simultaneously performing the pumping step, the scavenging step including returning the lubricant to a reservoir. 
     
     
       6. The method according to  claim 1 , wherein the pumping step includes pumping the lubricant to at least two bearing compartments. 
     
     
       7. The method according to  claim 1 , wherein the junction is upstream of an inlet to the bearing compartment. 
     
     
       8. The method according to  claim 1 , wherein the reservoir conduit is gravitationally above the junction. 
     
     
       9. The method according to  claim 1 , comprising:
 pumping the lubricant from the main pump to a second bearing compartment via a second supply line.